<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        html,body{
            height: 100%;
        }
        body{
            position: relative;
        }
        img{
            width:400px;
            position: absolute;
            left:50%;
            top:50%;
            transform: translate(-50%,-50%)
        }
    </style>
</head>
<body>
    <img src="images/phone.png" alt="">
</body>
</html>